It is the aim of the proposed research to gain an understanding of how Streptomycetes elaborate the nitrogen-nitrogen bonds which occur in a number of antibiotics. The antibiotics to be studied are streptozotocin, N-acetyl-6-diazo-5-oxy-L-norleucine (N-acetyl-DON); and elaiomycin and the antifungal agent LL-BH872 alpha as representatives of compounds containing aliphatic N-nitroso; -diazo; and -azoxy functionalities, respectively. These antibiotics are of clinical and/or experimental interest since they are known to act either as anticancer, as diabetogenic or as carcinogenic agents. No information is presently available on the biosynthesis of any one of these agents. Initial feeding experiments will be concerned with the establishment of the biosynthetic prescursors of their carbon skeletons. These will be followed by detailed investigations of the origin of the linked nitrogen atoms using 15N labeled precursors and mass spectral and Fourier Transform 15N nuclear magnetic resonance spectroscopic analysis to localize the labeled atoms in the respective antibiotic. Further studies will then be carried out at the enzymatic level to explore the biochemical steps and mechanisms involved in nitrogen-nitrogen bond biosynthesis. Special emphasis will be placed on the origin and the fate in the living cell of nitrous acid which is assumed to play a key role in some of the biosynthetic pathways. It is anticipated that the knowledge to be gained in this research may have an important bearing on our general understanding of the biosynthesis of N-nitroso- and azoxy carcinogens and of antineoplastic agents containing nitrogen-nitrogen bonds. This knowledge may be of importance in attempts to interfere with such carcinogen biosynthesis or, alternatively, to enhance the production of desired compounds.